The area covered by a cellular network is divided into a plurality of cells or cell sectors. Each cell or cell sector is served by a base station which transmits signals to and receives signals from mobile stations located in the cell or cell sector associated with the respective base station. Signals transmitted from a base transceiver station to a mobile station are referred to herein as “downlink signals” and signals transmitted from a mobile station to a base station are referred to herein as “uplink signals”. The downlink communication stream received by a mobile station from its base station can comprise packets which may be transferred in the form of a plurality of smaller component parts, referred to herein as payload units. The payload units together make up the original packet. These packets can include control information and/or data. The uplink communication stream received by the base station from each mobile station may comprise similar packets.
The term “packet” used herein refers generally to the packet of data which is to be transferred using the allocated communication resources. Typically, the packets comprise data generated by users and/or applications. Thus, examples of packets include user data documents, such as zip files and emails, digitised speech, video and other similar types of data files.
Network control elements manage the allocation of communication resources to allocate the downlink and uplink radio channels which are used for the transmission of the packets. One type of communication channel is known as a common communication channel. On this type of channel, the base station transmits information which may be intended for a number of the mobile stations within its cell or cell sector. A given packet may be intended for all the mobile stations or only for one of the mobile stations. Thus, a mobile station within the cell or cell sector monitors the or each common channel for packets intended for that mobile station. At least one common communication channel is generally continually in existence between a base station and at least some of the mobile stations within its cell or cell sector. Common channels can also be provided in the uplink direction.
Another type of communication channel is known as a dedicated communication channel. Dedicated channels are channels which are established only between the base station (or the base station subsystem) and the mobile station involved in a given communication. Packets to only a single mobile station can be contained in a dedicated channel. The information in the form of packets is then transmitted to the destination mobile station using the dedicated channel. Dedicated channels can be provided in the uplink direction. Alternatively, the direction of data transfer in a dedicated channel can be in both the uplink and downlink directions.
Known methods for allocating communication resources in cellular radio networks in which packets are transferred are inefficient in that they do not optimise the use of the air interface in either the uplink or downlink direction. For example, existing methods for allocating radio resources tend to be based on a buffer allocation status and/or data transfer rate considerations.
If radio resource allocation is based on the buffer allocation status, the result can be that radio resources are negotiated several times for each packet. For example, a large zip file of 1 mbyte in size would typically be divided into a plurality of smaller payload units, each payload unit having a size of say 10 bytes to 1K. All of the payload units may not have been received in the buffers when the radio resource allocation process is initiated, and thus a further allocation process is required once the remainder of the payload units have been received in the buffers.
Where allocation of radio resources is performed based on data transfer rate considerations, the system can suffer from unnecessary reservation of radio resources and/or many resource allocation changes, each of which requires a repeat of the negotiation process.
Thus, known methods result in unnecessarily complicated resource negotiation processes and may result in a dedicated channel being unnecessarily provided. This will inevitably reduce available radio resources.
Embodiments of the present invention seek to provide an improved method for the allocation of communication resources.